XRT72L13 Datasheet, PDF (249/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

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PRELIMINARY
XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
.
FIGURE 64. BEHAVIOR OF THE "TERMINAL INTERFACE" SIGNALS BETWEEN THE "TRANSMIT PAYLOAD DATA INPUT
INTERFACE" BLOCK (OF THE XRT72L13) AND THE TERMINAL EQUIPMENT (FOR MODE 1 OPERATION)
Terminal Equipment Signals
DS3_Clock_In
DS3_Data_Out
Tx_Start_of_Frame
DS3_Overhead_Ind
Payload[4702] Payload[4703]
X-Bit
Payload[0]
XRT72L13 Transmit Payload Data I/F Signals
RxOutClk
TxSer
Payload[4702] Payload[4703]
TxFrame
TxOH_Ind
X-Bit
Payload[0]
DS3 Frame Number N
Note: TxFrame pulses high to denote
DS3 Frame Boundary.
Note: TxOH_Ind pulses high to
denote Overhead Data
(e.g., the X-bit).
DS3 Frame Number N + 1
Note: X-Bit will not be processed by the
Transmit Payload Data Input Interface.
How to configure the XRT72L13 into the "Serial/
Loop-Timed/Non-Overhead Interface" Mode
1. Set the "NibIntf" input pin "low".
2. Set the "TimRefSel[1:0]" bit fields (within the
"Framer Operating Mode Register") to "00"; as
illustrated below.
OPERATING MODE REGISTER (ADDRESS = 0X00)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT2
BIT 1
BIT 0
Local Loop-
back
Mode
Line Loop-
back
Mode
Internal
LOS Enable
RESET
R/W
R/W
R/W
R/W
0
0
1
0
3. Interface the XRT72L13, to the Terminal Equip-
ment, as illustrated in Figure 63 .
NOTE: The XRT72L13 Framer IC cannot support the
“Framer Local Loop-back” Mode of operation, when operat-
ing in the “Loop-Timing” Mode. The user must configure
the XRT72L13 Framer IC into any of the following modes,
prior to configuring the “Framer Local Loop-back” Mode.
• Mode 2 - Serial/Local-Timed/Frame-Slave Mode.
• Mode 3 - Serial/Local-Timed/Frame-Master Mode.
Interrupt
Enable
Reset
Frame Format
TimRefSel[1:0]
R/W
R/W
R/W
R/W
1
0
0
0
• Mode 5 - Nibble-Parallel/Local-Timed/Frame-Slave
Mode.
• Mode 6 - Nibble-Parallel/Local-Timed/Frame-Mas-
ter Mode.
For more detailed information on “Framer Local Loop-
back” Mode of operation, please see Section 6.0.
4.2.1.2 Mode 2 - The "Serial/Local-Timed/
Frame-Slave" Mode
Behavior of the XRT72L13
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